Re: gdk_draw_image with alpha compositing on X?

["Matthew Allen" <list sydneyband com au>]

---------- Original Message ----------
To: Matthew Allen (list sydneyband com au)
From: Tor Lillqvist (tml iki fi)
Subject: Re: gdk_draw_image with alpha compositing on X?
Date: 3/10/2010 4:42:34a

> > I'm calling gdk_draw_image with a 32-bit per pixel image with some
> > pixels having alpha=0 and some with alpha=255, and the transparent
> > pixels come through as black (not surprisingly). What is the correct was
> > to get that on to the screen? (for Win32 and X)
>
> For Windows, you can't do any per-pixel alpha in GTK+, sorry.
> ("patches welcome")

On windows it's EASY to add per pixel alpha for blt'ing, just use the method AlphaBlend, however on Linux I'm 
not sure. Should I be going via Cairo to a client side window? Is that whats supposed to happen? Do the 
client side windows get rendered to a backing store in memory somewhere?

And yes, I can patch GTK+ to use AlphaBlend, but I wouldn't know how to integrate it nicely. Maybe if someone 
outlines some pseudo code or something I could go in and hack something up. Or even where I should make 
mods...
--
Matthew Allen